Background The precise mechanism involved in the acquisition of the IL‐17+ profile of γδT cells, the ligands responsible for this change, and whether this default is acquired during intrathymic maturation need to be elucidated. Objective This study aimed to evaluate whether IL‐17‐producing γδT cells are present in the airways of tolerant offspring from allergen‐sensitized mothers and the possible implication of maternal IgG in the generation of these cells. Methods Female mice were immunized or not, and the allergic response, frequency of γδT cell subsets and cytokine production of the offspring were analysed by flow cytometry. The effects of passive in vivo transfer of purified IgG were investigated in offspring. A translational approach was employed to analyse γδT cells in the thymus and PBMCs from humans. Results Maternal immunization reduced the frequency of spontaneous IL‐17‐producing γδT cells in the thymus, spleen and lung of offspring. This effect was mimicked by the in vivo treatment of females with purified IgG. IgG directly interacted with γδT cell membranes. The modulatory effect of human IgG on human infant intrathymic and adult peripheral γδT cells showed similarities to murine γδT cells, which is rarely reported in the literature. Conclusions & Clinical Relevance Together, our results reveal that IgG from potentially tolerant atopic mothers can influence offspring thymic IL‐17‐producing γδT cell maturation. Furthermore, we suggest that IgG is an unprecedented modulatory factor of murine and human γδT cells. These observations may support the future development of IgG‐based immunoregulatory therapeutic strategies.

Background Atopic dermatitis (AD) pathogenesis still needs to be elucidated, but invariant natural killer T (iNKT) cell involvement was already described by several groups. Our group has demonstrated that IgG antibodies purified from AD patients can modulate cytokine production by thymic T cells. Here we aimed to investigate if IgG from AD patients can modulate infant non-atopic thymic iNKT cells cytokine production in order to collaborate with the elucidation of AD development in infancy.Methods Thymic tissues were obtained from children from non-atopic mothers, and IgG was purified from AD patients diagnosed as moderate or severe and, as controls, from subjects clinically classified as non-atopic individuals. PBMCs from non-atopic individuals were also used in this study. ResultsOur results demonstrated that IgG from AD patients could induce non-atopic children thymic iNKT cells to produce higher levels of intracellular IL-4, IL-10, and IL-17 when compared to all control conditions. No effect was observed in non-atopic adults peripheral iNKT. We also observed that IgG from AD patients induces an increase in the expression of CD4 and Rorct transcription factor in non-atopic children thymic iNKT cells compared to the condition of all controls.Conclusions These observations suggest that IgG from AD patients can induce a cytokine profile by thymic iNKT cells from non-atopic infants compatible with the observations in AD development, which can collaborate with the elucidation of AD pathogenesis.

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